Box constituting vacuum insulated walls of a refrigerator or freezer cabinet

Abstract: At a box (10) constituting heat insulating walls of a refrigerator or freezer cabinet, which walls are formed by an inner shell (12) of metal, an outer shell (14) of metal and an evacuated heat insulation between the shells, the shells at a rectangular access opening (16) to the box show edges which are folded towards each other so that they form plane surfaces (18) located in substantially the same plane, which edges are gas-imperviously connected to each other by a thin metal strip (22) having a bad heat conductivity, which strip (22) is soldered to the surfaces (18).

Description: The invention refers to a box constituting heat insulating walls of a refrigerator or freezer cabinet, which walls are formed by an inner shell of metal, an outer shell of metal and an evacuated heat insulation between the shells which at a rectangular access opening to the box show edges, which are gas-imperviously connected to each other by a thin metal strip having a bad heat conductivity. Such a box is known through US patent No. 2 164 143. The heat insulation consists of a powder, which is under vacuum. The strip, the object of which is to prevent air from entering the insulation simultaneously as it shall prevent heat from being conducted from the outer shell to the inner shell, shows a bent cross section. As a consequence of this the joints of the strip at the corners of the access opening become bent, which joints as a consequence of the bent shape are complicated to make. The object of the invention is to bring about a connection between the edges of the shells of a box of the kind introductorily set forth, which connection is easy to manufacture. This object is obtained through the box according to the invention thereby that the edges are folded towards each other so that they form plane surfaces located in substantially one and the same plane as said access opening, and crevices, which occur after the folding at corners between adjoining surfaces, are filled by weld material or welded-on plate pieces and made even so that a good backing surface for the strip is obtained also at the corners, and that the strip is soldered to the plane surfaces and to said backing surfaces at the corners. It shall be pointed out that, through GB patent No. 1 061 204, it is known per se to bridge an edge surrounding a plane, vacuum insulated panel by soldering on thin strips of a material conducting heat badly. The strip, which is broader than the panel, is folded over the panel and is soldered to the panel with its folded part. This method to fold and fasten the strip is, however, not suitable for bridging the edge around an access opening of a box, especially not at the corners of the access opening. DE-A-1 501 237 discloses a strip for bringing about a heat insulating bridge between inner and outer shells around the inside of an access opening of a refrigerator or freezer cabinet. The ends of the shells are folded towards each other and form beds located in four different planes for the strip, which can be constituted by a single strip extending continuously about the opening. The strip is made of plastic and rests on the beds and is kept on place by form details of the strip, which details also can be held by insulating foam which has been introduced between the shells. Here, where any pressure difference will not prevail between the foam on the inside of the strip and the atmosphere on the outside of the strip, it is not question about that the strip shall form a gas-impervious bridge, which effectively prevents gases from entering into a vacuum insulation. An embodiment of a box according to the invention is described below in connexion with the attached drawing, in which Fig. 1 shows the box looked at against an access opening, Fig. 2 shows a sectional view according to the marking II-II in Fig. 1 with the box brought onto a fixture, Fig. 3 shows in the same view as Fig. 1 the box with strips soldered on around the access opening, Fig. 4 shows an enlargement of the upper left corner in Fig. 3, Fig. 5 shows a sectional view according to the marking V-V in Fig. 4, and Fig. 6 shows a perspective view of a refrigerator or freezer cabinet, of which the box is a part. By 10 is designated a box consisting of an inner shell 12 of iron plate, e.g. 0,6 mm thick, and an outer shell 14 of iron plate, e.g. 0,6 mm thick. At a rectangular access opening 16 to the box the edges of the shells are folded towards each other, so that they form plane surfaces 18, which are located in one and the same plane. In Fig. 2 the shells are placed on a fixture 20, which keeps the surfaces mutually fixed, when a plane strip 22, which bridges a gap 24 between the shells at the access opening, by means of a solder is soldered to the surfaces 18. The melting of the solder can be done in inductive way by means of two coils 25, which heat the shells 12 and 14, which in their turn heat the solder. In order that the heat leakage through the strip 22 shall become small, a strip 22 is chosen, which is as thin as possible, e.g. 0.05 mm, of a material, e.g. stainless steel, which conducts heat badly. In Fig. 3 is shown how the gap 24 has been sealed by four, straight strips 22, which overlap each other at the corners 26 of the access opening. Such a corner is shown in enlargement in Figs. 4 and 5. The solder also connects the strips mutually, where they overlap each other. The surfaces 18 are suitably constituted by a part of the respective shell folded 90°. Crevices, which occur after the folding at corners 19 between adjoining surfaces 18, are filled, before the strips 22 are soldered on, by weld material or welded-on plate pieces and are made even, so that a good backing surface for the strips is obtained also here. When the strips 22 have been soldered to the edges around the access opening 16 and have been soldered mutually together at the corners, the space between the shells is filled with a heat insulating powder 28, after which the space is evacuated and sealed. A frame 30 of plastic is fastened outside the strips 22 to protect them against mechanical damage. The box 10 is equipped with a door 32, see fig. 6, and a refrigerating apparatus (not shown) and is after surface conditioning ready to be used as a refrigerator or freezer 33. The door 32 is journalled in arms 34, which are fastened to the shell 14. A seal 36, which is fastened to the door, seals against the frame 30, when the door is closed. The box 10 with the door 32 and the refrigerating apparatus can also be used as a refrigerator or freexer box with the access opening located in a horizontal plane. Furthermore the box 10 with the door 32 can be used without a refrigerating apparatus as a heat insulating cabinet. The door 32 can consist of an element with one iron plate forming the outside and edges of the door and one iron plate forming the inside of the door, which plates enclose an evacuated heat insulation. A gap runs between the plates around the inside of the door close to its periphery. Adjacent to the gap the plates show plane surfaces located in one and the same plane like the surfaces 18. Heat is prevented from being conducted through the plates from the outside to the inside of the door by thin metal strips, which in the same way as the strips 22 bridge the gap and are soldered to the surfaces.

Claims: A box (10) constituting heat insulating walls of a refrigerator or freezer cabinet (33), which walls are formed by an inner shell (12) of metal, an outer shell (14) of metal and an evacuated heat insulation (28) between the shells which at a rectangular access opening (16) to the box show edges, which are gas-imperviously connected to each other by a thin metal strip (22) having a bad heat conductivity, characterized in that the edges are folded towards each other so that they form plane surfaces (18) located in substantially one and the same plane as said access opening (16), and crevices, which occur after the folding at corners (19) between adjoining surfaces, are filled by weld material or welded-on plate pieces and made even so that a good backing surface for the strip is obtained also at the corners, and that the strip (22) is soldered to the plane surfaces (18) and to said backing surfaces at the corners. Arrangement according to claim 1, characterized in that two strips (22) overlap each other and are soldered to each other and to the surfaces (18) at the respective corner (26) of the access opening (16).

Inventors: DELLBY FREDRIK, FONSER PER AKE, DELLBY, FREDRIK, FONSER, PER AKE
Applicants: ELECTROLUX AB, AKTIEBOLAGET ELECTROLUX
Application year: 1994
Main classification: F25D23
IPC codes: F25D23